Narrowband positioning reference signal configuration

Abstract

Systems and methods for configuring Narrowband Positioning Reference Signals (NPRS) for NB-IoT are provided. A network node generates and transmits NPRS configuration information including a first NPRS bitmap for FDD mode and/or a second NPRS bitmap for TDD mode. A wireless device can determine a NPRS configuration in accordance with the second NPRS bitmap for TDD mode and perform measurements using the NPRS configuration.

The invention claimed is: 
     
       1. A method performed by a wireless device, the method comprising:
 receiving Narrowband Positioning Reference Signal (NPRS) configuration information for a cell, the NPRS configuration information including at least one of a first NPRS bitmap for Frequency Division Duplex (FDD) mode and a second NPRS bitmap for Time Division Duplex (TDD) mode, wherein the second NPRS bitmap for TDD is shorter in length than the first NPRS bitmap for FDD, and wherein the second NPRS bitmap for TDD is less than 10 bits in length; 
 responsive to determining that the cell operates in TDD mode, determining a NPRS configuration in accordance with the second NPRS bitmap for TDD mode; and 
 performing measurements using the NPRS configuration. 
 
     
     
       2. The method of  claim 1 , further comprising, transmitting a capabilities indication indicating the wireless device supports TDD mode. 
     
     
       3. The method of  claim 2 , wherein transmitting the capabilities indication is responsive to receiving a capabilities request. 
     
     
       4. The method of  claim 1 , wherein determining the NPRS configuration includes mapping the second NPRS bitmap to subframe numbers. 
     
     
       5. The method of  claim 1 , wherein performing measurements includes estimating time of arrival (TOA) signals from at least one radio access node. 
     
     
       6. The method of  claim 1 , wherein performing measurements includes determining Observed Time Difference of Arrival (OTDOA) measurements. 
     
     
       7. The method  claim 1 , further comprising, transmitting at least one measurement report. 
     
     
       8. The method of  claim 1 , wherein the wireless device is a Narrowband Internet of Things (NB-IoT) FDD device configured to perform measurements on a NB-IoT TDD downlink carrier. 
     
     
       9. A wireless device comprising a radio interface and processing circuitry configured to:
 receive Narrowband Positioning Reference Signal (NPRS) configuration information for a cell, the NPRS configuration information including at least one of a first NPRS bitmap for Frequency Division Duplex (FDD) mode and a second NPRS bitmap for Time Division Duplex (TDD) mode, wherein the second NPRS bitmap for TDD is shorter in length than the first NPRS bitmap for FDD, and wherein the second NPRS bitmap for TDD is less than 10 bits in length; 
 responsive to determining that the cell operates in TDD mode, determine a NPRS configuration in accordance with the second NPRS bitmap for TDD mode; and 
 perform measurements using the NPRS configuration. 
 
     
     
       10. The wireless device of  claim 9 , further configured to transmit a capabilities indication indicating the wireless device supports TDD mode. 
     
     
       11. The wireless device of  claim 10 , wherein transmitting the capabilities indication is responsive to receiving a capabilities request. 
     
     
       12. The wireless device of  claim 9 , wherein determining the NPRS configuration includes mapping the second NPRS bitmap to subframe numbers. 
     
     
       13. The wireless device of  claim 9 , wherein performing measurements includes estimating time of arrival (TOA) signals from at least one radio access node. 
     
     
       14. The wireless device of  claim 9 , wherein performing measurements includes determining Observed Time Difference of Arrival (OTDOA) measurements. 
     
     
       15. The wireless device of  claim 9 , further configured to transmit at least one measurement report. 
     
     
       16. The wireless device of  claim 9 , wherein the wireless device is a Narrowband Internet of Things (NB-IoT) FDD device configured to perform measurements on a NB-IoT TDD downlink carrier. 
     
     
       17. A method performed by a network node, the method comprising:
 obtaining Narrowband Positioning Reference Signal (NPRS) configuration and one of Frequency Division Duplex (FDD) and Time Division Duplex (TDD) mode information associated with a cell; 
 responsive to determining that the cell operates in TDD mode, generating NPRS configuration information for the cell, the NPRS configuration information including a NPRS bitmap for TDD mode, wherein the NPRS bitmap for TDD is shorter in length than an NPRS bitmap for FDD, and wherein the second NPRS bitmap for TDD is less than 10 bits in length; and 
 transmitting the NPRS configuration information to a wireless device. 
 
     
     
       18. A network node comprising a radio interface and processing circuitry configured to:
 obtain Narrowband Positioning Reference Signal (NPRS) configuration and one of Frequency Division Duplex (FDD) and Time Division Duplex (TDD) mode information associated with a cell; 
 responsive to determining that the cell operates in TDD mode, generate NPRS configuration information for the cell, the NPRS configuration information including a NPRS bitmap for TDD mode, wherein the NPRS bitmap for TDD is shorter in length than an NPRS bitmap for FDD, and wherein the second NPRS bitmap for TDD is less than 10 bits in length; and 
 transmit the NPRS configuration information to a wireless device. 
 
     
     
       19. The network node of  claim 18 , further configured to receive a capabilities indication indicating that the wireless device supports TDD mode. 
     
     
       20. The network node of  claim 19 , wherein receiving the capabilities indication is responsive to transmitting a capabilities request. 
     
     
       21. The network node of  claim 18 , wherein transmitting the NPRS configuration information is responsive to receiving a positioning request. 
     
     
       22. The network node of  claim 18 , wherein the length of the NPRS bitmap for TDD mode is based at least in part on an available number of downlink subframes. 
     
     
       23. The network node of  claim 18 , wherein the NPRS configuration information includes an indication of whether an NPRS carrier is an anchor carrier. 
     
     
       24. The network node of  claim 18 , wherein generating the NPRS bitmap for TDD mode includes removing at least one of a subframe used for uplink in TDD and a special subframe for TDD. 
     
     
       25. The network node of  claim 18 , wherein generating the NPRS bitmap for TDD includes removing a subframe used for at least one of Narrowband Primary Synchronization Signal (NPSS), Narrowband Secondary Synchronization Signal (NSSS), and Narrowband Physical Broadcast channel (NPBCH). 
     
     
       26. The network node of  claim 18 , further configured to derive a positioning estimate for the wireless device in accordance with a received measurement report.